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hkmaly

NP Friday, Aug 16, 2019

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41 minutes ago, Pharaoh RutinTutin said:

Why use pure Oxygen and not ordinary air?

$10,000 per pound.

In the era of the Space Shuttle, the cost of launching payload into orbit was approximately $10,000 per pound.  The price, proportionally, would possibly be higher back in the Apollo era.  So why load up pressurized tanks full of inert gasses the astronauts did not need to breathe?

There is a long tradition in almost every human endeavour of ignoring possible problems, if the preventive solution would be difficult or expensive, until after an actual disaster demonstrates the need to implement that solution.

It was a ground test, no intention to launch that day. In this case, running an integrity test with oxygen vs air was also not cost effective, in addition to being a deadly error.

It is possible that oxygen was intentionally used to confirm there was no fire hazard, in which case including the astronauts was really stupid.

 

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13 hours ago, Darth Fluffy said:

It was a ground test, no intention to launch that day. In this case, running an integrity test with oxygen vs air was also not cost effective, in addition to being a deadly error.

It is possible that oxygen was intentionally used to confirm there was no fire hazard, in which case including the astronauts was really stupid.

It's possible that in name of faster progress, they decided to do multiple tests at once instead of one after another.

Still, someone should've re-read those tests and think about possible conflicts ...

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On 8/20/2019 at 1:44 AM, hkmaly said:

There is no exercise without ATP and no oxygen is needed for "burning" ATP. Now, for creating it ... I think you can get like 30 ATP from single sugar molecule WITH oxygen and 2 WITHOUT.

Right, sorry it’s been 30+ years since I did the Krebs Cycle. I meant to make the point that your body can function without oxygen, but very inefficiently and at high cost (like lactic acid build up and other problems) and not for very long. Since your brain is an organic computer, when you stop breathing it’s like losing power and your body only has so much reserve power. The thing is, you don’t have a direct oxygen sensor system, your body senses the concentration of CO2 to prod you to breathe.

I’m remembering all this from a multidisciplinary scuba class I took at university 30+ years ago (there was a oceanography school there) and we were required to be able to hold our breath for 3 minutes underwater and encouraged to aim for 5.  The biomechanics were explained as part of the instruction, so if the current understanding of the biofeedback loop has changed I apologize. 

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15 hours ago, Skip said:

I’m remembering all this from a multidisciplinary scuba class I took at university 30+ years ago (there was a oceanography school there) and we were required to be able to hold our breath for 3 minutes underwater and encouraged to aim for 5.  The biomechanics were explained as part of the instruction, so if the current understanding of the biofeedback loop has changed I apologize. 

Sounds dangerously risky.

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14 minutes ago, The Old Hack said:
1 hour ago, hkmaly said:

Sounds dangerously risky.

To be fair, I can't offhand think of any activity I would describe as safely risky.

I do. Almost any computer game. Those are full of risky stuff which are only dangerous for your character and totally safe for you. At least assuming you don't take them too seriously.

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5 hours ago, The Old Hack said:
5 hours ago, hkmaly said:

I do. Almost any computer game. Those are full of risky stuff which are only dangerous for your character and totally safe for you. At least assuming you don't take them too seriously.

Good point!

I cringe every time I'm playing a skyblock modpack in minecraft and need to expand my platform...

That usually lasts until I get some sort of creative flight.

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14 hours ago, hkmaly said:

Sounds dangerously risky.

My instructors tended towards overkill. They were oceanographers and US Navy divers doing graduate work at the Naval War College (it’s right across the bay from the oceanography school.) To be fair it was in the pool and it did pay off for one student. She had her regulator fail at around 100 ft. And her buddy was one of the SEAL instructors. She swam over to him, signaled her loss of air, and used his secondary regulator to ascend with him.  She was so calm the instructor thought one of his friends or professors we were diving with had put her up to it.  

In order to even dive in open water we were required to drop our weight belt, mask and snorkel at the bottom of the high dive pool, then surface dive in full winter wet suit back down, put the weight belt back on, put the mask on and clear it of water, put the snorkel in and ascend slowly to clear the snorkel. That’s not part of any civilian scuba training, but I never felt ill prepared for any dive I ever did. 

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